Hydropneumatic tank



Patented May 4, 1943 UNITED STATES PATENT OFFICE HYDROPNEUMATIC TANK J ehn A. Dodd, Atlanta, Ga. Application september 1s, 1940, smal No. 356,598

(ci. a- 0) 4 Claims.

The present invention relates to hydro-pneumatic tanks, and more particularly to a control for maintaining therein the proper volume of air in relation to the volume of water.

In water systems wherein water automatically is pumped intermittently as required into a relatively small tank for storage under pressure and maintained under pressure by a body of air, it is necessary for proper and economical operation to employ in the tank a volume of air having a given relation to the volume of Water. Should there be too great a proportion of air the water capacity of the tank is made too small and if there is too great a proportion of water, the pressure falls on too quickly as the water is drawn from the tank. Due to the fact that water is drawn from the small storage tank intermittently, and also to the fact that air above the Water is absorbed thereby, there is encountered a problem of considerable diiliculty to maintain the proper relation between the volume of Water in relation to the volume of air under all/conditions of operation. The problem is further complicated by the fact that the water level in the tank varies within limits dur-v According to the present invention the ing use. air pressure control is under the control of the water supply control as well as the pressure of the air in the tank.

An object of the invention is to provide a combination air pressure and water level control, which automatically supplies air to a hydropneumatic tank as air is needed to maintain a desired volume of air in relation to the volume of water.

Another object of the invention is to control the air supply by the WaterY level and the pressure of the air in the tank.

Still another object of the invention is to provide an electrical control system for maintaining the water level in a hydro-pneumatic tank between a predetermined maximum and minimum level and to operate air supplying means in relation to the water level maintaining means. Y

These and other objects residing in the arrangement, combination, and construction of parts will be apparent from the following speciication When taken with the accompanying drawing, in which:

Fig. 1 is a view partly diagrammatic disclosing a hydro-pneumatic tank according to the present invention, parts of the structure associated therewith being shown diagrammatically and,

Fig. 2 is a diagrammatic illustration of the electrical circuit.

VReferring to the drawing, the referencechar- Y in the tank'l reaches a acter I indicates a tank provided withan outlet pipe 2 and an inlet pipe 3. The tank I is for storing and delivering under pressure a liquid, usually, but not necessarily, water. However the liquid should be a conductor of electricity. Liquid level 4 as shown. Above the level `1I is an air space 5.

The inlet 3 is connected to a pump 6 which is driven by a motor 1 disclosed in Fig. 2. Communicating with the air space 5 of the tank I is an air inlet conduit 8 which is connected to a compressor 9, driven by a motor I0, disclosed in Fig. 2. It will-be understood that the compressor S and its motor I0 may havesubstituted therefor an electrically operated valve for directing the air under pressure from a suitable source into the conduit 8, and also that the quantity of air delivered be within a range which will permit the system to cycle as hereinafter described.- .Also communicatiing with the air space 5 of the tank I is a pressure responsive switchl I, shown in Fig.- 1 and diagrammatically illustrated in Fig. 2. The pressure responsive switch II is for controlling the inlet of -air into the chamber I5 whenthe pressure therein falls below a predetermined maX- imum, although as hereinafter explained, its'circuit is open While the motor 1 is in operation. A safety relief valve I2 may be provided, if desired, to communicate with the air space 5.

Disposed at one side or" the tank I is an auxiliary tube I5, communicating with the tank I at the bottom thereof, through a pipe I6, and at the top thereof, through a pipe I1 in a manner that will be understood by those skilled in the art. Disposed Within the tube I5 is a long electrode I3 and a short electrode I9. The electrodes I8 and I9 are insulated from each other and from the tube I5. Also, they are provided .with connecting Wires 31 and 36 respectively. It will be understood that the liquid level 4 within the tank I will be the liquid level within the tube I 5, due to the communication with the tube I5 provided by the pipes I6 and I1. The electrodes I8 and I9 are for the purpose of controlling through the circuits disclosed in Fig. 2 the level 4 of the liquid Within the tank I.

Referring particularly to the Wiring diagram in Fig. 2, there is disclosed a relay for controlling the operation of the-pump motor 'I and the compressor motor l0. The relay consists of a magnetic core 25 having a cross piece 26 and another cross piece 21. Legs 28 connect the cross pieces 26 and 21 and constitute magnetic poles.

A primary coil 29 is disposed about the cross piece 26 and is permanently connected'across the electric wires 30 and 3l connected to a source of electric current, while the apparatus is in operation. Disposed about the cross piece 21 is a reaction coil 32, which is grounded at one end as at 33. The opposite end is connected by a conductor 34 to a contact 35 which is in turn connected by a conductor 36 to the short elec- An armature 45 pivoted at 46 is arranged for association with the legs or poles 28 and is pivoted away from the poles 28 by the action of a spring 41, anchored to a xed point 48. The armature 45 carries a switching arm 49 provided with a conducting bridging member 50 on which there are arranged contacts I and 52. Disposed in the path of movement of the contacts 5I and 52 are contacts 53 and 54 respectively. The contact 54 is connected directly to the -main line conductor 36 and the contact 53 is connected to the main line conductor 3l through the pump motor 1. In the position shown with the armature 45 away from the poles 28, under the action of the spring 41, the bridging member 50 completes the pump motor 1 circuit, through the main line conductor 36, the contact 54, the contact 52, the bridging member 58, the contact 5I, and the contact 53. Thus, as the armature f45 moves toward and away from the poles 2-8, the

pump motor 1 circuit is opened and closed respectively.

Also connected to the switching arm 49 is a conducting bridging member 6I, provided with contacts 62 and 63. Disposed in the path of movement of the contacts 62 and 6 3 are contacts 64 and 65 respectively. The Contact 65 is connected to the main line conductor 3I by a condoctor 66 and the contact 64 is Connected to the compressor motor I9 by a conductor 61.

The pressure responsive switch I I lis diagrammatically shown as comprising a chamber communicating with the air space 5 through a conduit 69, and a pressure responsive diaphragm 19. The diaphragm 16 has connected thereto an arm 1I movable therewith and on which is mounted a contact 12. Associated therewith and in the path of movement of the contact 12 is a fixed contact 13. The contacts 12 and 13 are spaced so that when the air pressure in the air space 5 of the tank I falls below apredetermined maximum, the .contact `1.2 is moved into engagement with the contact 13.

The compressor motor I6 is connected by a conductor 14 to the contact 13 and the contact 12 is connected to the main line conductor 30 by a conductor 15. Thus, as the switching arm 49 moves under the action of the armature 45, to the right as shown in Fig. 2, the compressor motor I0 circuit is closed, the circuit including the main line conductor 3 l the conductor 66, the contacts 65 and 63, the bridging member 6I, the contacts 62 and 64, the conductor 61, the compressor motor I6, the conductor 14, the contacts 13 and 12 of the pressure responsive switch Il, the conductor 15, and themain line conductor 36. It will be understood that as the armature 45 moves toward and away from the poles 28, the

bridging member 6I moves respectively to close and open the compressor motor II) circuit.

f For moving the switching arm 38 in timed relation with the switching arm 49, there is provided a connecting link 16, it being understood that the general arrangement of all the contacts disclosed is that when the contacts 52 and 54, and 5I and 53 are closed, the contacts 40 and 35 are opened, and the contacts 63 and 65, and 62 and 64 are open. Also, when the contacts 52 and 54, and 5I and 53 are open, the contacts 40 and 35, the contacts 63 and 65, and the contacts 62 and 64 are closed.

The control device is designed particularly for use with alternating current and in this regard, the use of alternating current eliminates electrolytic action which would otherwise be set up within the tube I5 by the use of direct current. Also, it will be understood that while the liquid in the tank I may be other than water, within the scope of the present invention, nevertheless when water is used, there are sucient impurities therein to make the same a conductor of electricity and therefore render the control device operative.

In the operation of the device, the primary coil 29 being constantly energized continuously sets up an alternating magnetic flux. The cross piece 21 constitute-s a shunt for the flux with the result that most of the flux passes in a path across the cross piece 21. While some ux may leak across the ends of the poles 28 the amount will be insuicient to attract the armature 45. In the position shown, the liquid level is above the bottom of theA long electrode I8 and below thev bottom of the short electrode I9. Also, the circuit of the pump motor 1 is closed so that the pump is pumping liquid into the tank I. As the liquid level 4 in the tank rises it will eventually come intocontact with the short electrode I9. This will complete a circuit through the conductor 36, the contact 35, the conductor 34, through the reaction coil 32 to the ground and through the ground to the water and the short electrode I9. Electric current is then induced into the circuit of the coil 32 and the eiect of this current is to set up a magnetic reaction to the flow of magnetic ux through the cross piece 21. Accordingly, the flux set up by the coil 29 seeks another path, and this path is across the poles 28 of the core 25. This flux seeking a path across the poles 28 is strong enough to attract the armature 45 and move the same to its dotted line position as shown in Fig. 1, opening the pump motor 1 circuit by separating the contacts 52 and A5I from the contacts 54 and 53, and closing the compressor motor Ii] circuit byv engaging the contacts 62 and 63 with the contacts 64 and 65, provided that the pressure responsive switch I I is closed. The closing of the compressor motor I6 circuit starts the entrance of air into the air space 5 of the tank I if the pressure in vthe tank I is below a predetermined maximum, since the compressor motor I0 circuit also includes the pressure responsive switch II. Assuming that the pressure in the tank I is below the predetermined maximum for which the pressure responsive switch II is set, andthe contacts 12 and 13 are therefore in engagement, the compressor motor I6 circuit will remain closed until the air pressure in tank I reaches the predetermined maximum and the contacts 12 and 13 separate, or until the armature 45 is moved away from the poles 28 to start the pump motor 1 by closing its circuit through the contacts V52 and 54, and 5I and 53, and the contacts 62 and 63 are separated from the contacts 64 and 65 in the compressor motor I circuit.

As explained hereinabove, when the rising liquid level reaches the bottom of the electrode I9, the circuit of the reaction coil 32 is closed through the conductor 35, the Contact 35, the conductor 34 and the ground at 33, withA the result that the armature 45 is drawn to the end of the poles 28. As the armature 45 is drawn against the end of the poles 28, the switching arm 49 moves to actuate the link 'I6 todraw the switching arm 38 to the right as shown in Fig. 2 to engage the contact 40 with the contact 35. Engagement of the con tacts 40 and 35 results in closing the reaction coil 32 circuit through the liquid in the tank I to the ground, the electrode I8, the connector 31, the switching arm 38, the contacts 40 and 35, and the conductor 34 through the coil 32 to the ground. Thus, when the liquid level 4 in the tank I drops below the bottom of the electrode I9, the reaction coil 32 circuit will remain closed through the last named circuit until the liquid level 4 drops below the level of the electrode I8, to break the connection between the electrode I8 through the liquid in the tube I to the ground. When this circuit, which constitutes a holding circuit, is broken, the shunt constituted by the cross piece 2'I is no longer choked, since there is no reaction set up by the coil 32 and the magnetic flux set up by the coil 29 passes through the cross piece 21 permitting the armature 45 to move away from the poles 28 and to be drawn to its full line position by the spring 41. The result is that the contacts 54 and 53 are engaged by the contacts 52 and 5I to close the pump motor 'I circuit to start the pump, and the contacts 62 and E3 are moved away from the contacts 64 and 65 to open the compressor motor IB circuit to stop the action of the compressor, should the compressor motor I0 circuit have not already been opened by the separating of the contacts 'I2 and 'I3 under the action of the pressure responsive switch I I.

It will be understood that while I disclose one form of relay 25, that other relays accomplishing the same result may be employed, inasmuch as the specific form of the relay employed forms no part of the present invention. Furthermore, the pump is to be considered broadly as to cover an injector or even a valve for closing and opening a conduit from a pump or gravity feed.

Having thus described my invention, what I desire to secure by Letters Patent and claim is:

1. An air volume control for a hydro-pneumatic tank comprising means to maintain the level of the liquid in the tank between a predetermined maximum and minimum level, means to direct air under pressure into the tank to maintain an air space over the liquid in the tank, said air directing means being under control cf means to render the same operative when the liquid in the tank reaches its maximum level and during the time the liquid in the tank is between its maximum and minimum levels following the liquid reaching its maximum level, and to render the same inoperative when the liquid in the tank reaches its minimum level, and also being under the control of pressure responsive means operatively connected to the tank for limiting the air pressure in the tank to a predetermined maximum.

2. An air volume control for a hydro-pneumatic tank comprising electrically controlled means to maintain the level of liquid in the tank between a predetermined maximum and minimum level, electrically controlled means to direct air under pressure into the tank, pressure responsive means operatively connected to the tank for limiting the air pressure in the tank to a predetermined maximum, an electric circuit including said liquid level maintaining means, said air directing means, and said pressure responsive means, means responsive to the liquid level in the tank for controlling said circuit for maintaining the liquid level in the tank between a predetermined maximum and minimum and for rendering operative said air directing means when the liquid level in the tank reaches said maximum, subject to the control of said pressure responsive means, and a holding circuit for maintaining said air directing means operative subject to the control of said pressure responsive means during the time the liquid level is dropping from said maximum to said minimum level.

3. A hydro-pneumatic system comprising a tank, a pump for replenishing the supply of a liquid in the tank, automatic means for controlling the operation of said pump to start the operation of said pump when the liquid level therein falls below a predetermined point and to stop the operation of said pump when the liquid level therein rises to a predetermined point, means to direct air under pressure into said tank to maintain an air space over the liquid in said tank, an operative connection between said air directing means and said controlling means for starting the operation of said air directing means when said pump stops upon the liquid in the tank reaching its maximum level and for stopping the operation of said air directing means when said pump starts upon the liquid in the tank reaching its minimum level, and pressure responsive means operatively connected to the tank for stopping the air directing means while the pressure in the tank is at or over a predetermined maximum, said air directing means being operative at all times between said pump stopping and starting points except when interrupted by said pressure responsive means.

4. In a device of the character described, a closed liquid container, a pump for pumping liquid into said container, means to draw liquid from said container, a pump circuit for said pump, an air compressor for increasing the air pressure in said container, a compressor circuit for said compressor, a pressure responsive switch in said compressor circuit responsive to the pressure in said container, means to close said pump circuit at one predetermined liquid level in said container and to open said pump circuit at a second predetermined liquid level in said container, said means opening said pump circuit closing said compressor circuit subject to the operation of said pressure responsive switch, and a holdingV circuit for holding said compressor circuit closed subject to said pressure responsive switch and said pump circuit open until said rst named liquid level is reached.

JOHN A. DODD. 

